Lateral entry insert for cup trial

ABSTRACT

Trials for a reverse shoulder system are described. The trials generally include an insert housed within a humeral cup. The insert has a proximal end and a distal end, the proximal end having a concave recess therein adapted to receive a glenosphere prosthesis. The distal end of the insert includes a shaft, the shaft is substantially housed within the confines of the humeral cup. A distal end of the humeral cup is inserted in a humeral stem.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 13/484,557, filed May 31, 2012, the disclosure of which isincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a shoulder trial for reverse shoulderarthroplasty (RSA), and in particular it relates to such a trialincluding an insert and humeral cup that are configured to engage oneanother by sliding the insert from a transverse or lateral directioninto engagement with the humeral cup.

BACKGROUND OF THE INVENTION

The successful outcome of RSA depends greatly on proper soft tissuetension in the shoulder joint. The stability of the shoulder joint isgenerally maintained from significant deltoid tension holding this balland socket joint together. Some RSA systems require the surgeon to use atrial and error approach in establishing proper soft tissue tension.Such approaches often take several attempts before adequate stability isachieved.

When performing a trialing step in a reverse shoulder procedure, oneimportant aspect is to determine the correct height of the humeralinsert implant that will ultimately be chosen for the patient. A seriesof humeral insert trials with varying heights is normally utilized todetermine the correct height for the implant. By using thicker orthinner insert trials the soft tissue tension and joint range of motioncan be optimized for the patient.

Such trialing procedures generally include selecting a first trialinsert, installing it into other parts of the shoulder system, reducingthe joint, and then checking the joint for soft tissue tension and rangeof motion. The joint is then dislocated, and if the correct humeralinsert implant height has been determined the reverse shoulderimplantation proceeds. When the correct trial is determined, the softtissue tension is significant, requiring the surgeon to apply extremeforce to the humerus and surrounding soft tissues to reduce the joint.If no additional damage is done during this reduction process, the jointmust then be dislocated to allow the surgeon to implant a jointreplacement prosthesis.

If the correct humeral insert height has not yet been determined, then asecond trial insert with a different thickness than the first trial isselected. The second trial insert is installed and the joint isassessed. As a result of the trialing procedure, the reverse shoulderjoint can be reduced and dislocated multiple times.

Traditionally, each time the reverse shoulder joint is reduced anddislocated, the soft tissue has to be stretched in order for theglenosphere to be placed in or removed from the humeral insert. Thisstretching of the soft tissue can lead to joint instability andincreased recovery time for the patient.

BRIEF SUMMARY OF THE INVENTION

The trial assembly of the present invention includes at least a trialcup and a trial insert. In one embodiment of the present invention, arecess or guide track of an insert trial is slid over a centering memberor positive stop pin on a cup trial. Flanges on the cup trial arereceived within a groove of the insert trial as the guide track is slidover the centering member. After the centering member is locatedadjacent the deepest part of the guide track, the insert trial ispreferably rotated in either a clockwise or counterclockwise directionsubstantially locking the lateral and vertical movement of the inserttrial with respect to the cup trial. The rotational movement of theinsert trial with respect to the cup trial can still occur.

The lateral engagement and disengagement of the insert trial and insertcup allows any size insert trial and cup to be used during the trialingprocess in contrast to having to reduce and distract the trials fromeach other prior to and after use.

In the past, there have been issues with achieving appropriatetensioning during RSA due to difficulties in inserting and removing thetrials from between the humeral components and the glenosphere componenton the glenoid. The trial assembly of the present invention provides away of reducing and dislocating the joint without any temporary increasein joint tension that is usually experienced when reducing the ball up,over, and into the insert trial socket.

In accordance with a first aspect of the present invention is a trialassembly comprising a trial cup and a trial insert. The trial cup has adistal end surface and a proximal end surface, the proximal end surfaceincluding first and second flanges and a centering member protrudingoutwardly therefrom. The trial insert includes a proximal end portionand a shaft portion having a distal end, the shaft portion having agroove around an outer circumference thereof and a recess in the distalend thereof. The trial insert is operatively coupled to the trial cupwhen the centering member is received in the recess of the trial insertand an engagement member on each of the first and second flanges isreceived within the groove of the trial insert.

In one embodiment of this first aspect, the trial assembly furtherincludes an elongate shaft having proximal and distal ends, the distalend surface of the trial cup adapted to lie adjacent to the proximal endof the elongate shaft when the trial cup is coupled to the elongateshaft.

In another embodiment of this first aspect, the first and second flangesof the trial cup extend outwardly from at least a portion of an outercircumference of the proximal end surface of the trial cup.

In yet another embodiment of this first aspect, the recess of the trialinsert begins at the outer circumference of the shaft portion andterminates adjacent a central axis of the trial insert. When alongitudinal axis of the centering member is collinear with the centralaxis of the trial insert, the trial insert may be rotated in a radialdirection about the central axis thereof. Further, rotating the trialinsert 90° in either a first or second radial direction about a centralaxis thereof results in lateral locking of the trial insert and trialcup such that the trial insert and trial cup cannot be uncoupled byoffsetting the longitudinal axis of the centering member of the trialcup and central axis of the trial insert. Further still, rotating thetrial insert another 90° in either a first or second radial directionabout the central axis thereof results in lateral unlocking of the trialinsert and trial cup such that the trial insert and trial cup can beuncoupled by offsetting the longitudinal axis of the centering member ofthe trial cup and central axis of the trial insert.

In still yet another embodiment of this first aspect, the proximal endportion of the trial insert has a concave recess therein.

In still yet another embodiment of this first aspect, the proximal endportion of the insert includes an outer face having a plurality ofcalibration marks arranged thereon. The calibration marks are preferablylocated at 90° increments.

In still yet another embodiment of this first aspect, an outer face ofthe insert includes a plurality of attachment locations adapted to beengaged by an adjustment tool for rotating the trial insert about thecentral axis thereof.

In still yet another embodiment of this first aspect, the proximal endsurface of the cup has a marker thereon.

In still yet another embodiment of this first aspect, a size or heightof the trial assembly is measured by the axial distance between aproximal end surface of the trial insert and the distal end surface ofthe trial cup.

In accordance with a second aspect of the present invention is a trialassembly comprising a trial cup and a trial insert. The trial cup has adistal end surface and a proximal end surface, the proximal end surfaceincluding first and second flanges about a circumference thereof and acentering member protruding outwardly along a central longitudinal axisthereof. The trial insert includes a proximal end portion and a shaftportion having a distal end, the shaft portion having a groove around anouter circumference thereof and a recess in the distal end thereof, therecess begins about a circumference of the shaft and terminates adjacenta central longitudinal axis of the trial insert. The trial insert isoperatively coupled to the trial cup when the centering member isreceived in the recess of the trial insert such that the centrallongitudinal axes of the centering member and trial insert are collinearand a portion of each of the first and second flanges is received atleast partially within the groove of the trial insert.

In one embodiment of this second aspect, when the central longitudinalaxes of the centering member and trial insert are collinear, the trialinsert may be rotated in a radial direction about the centrallongitudinal axis of the centering member. Further, rotating the trialinsert 90° in either a first or second radial direction about a centralaxis thereof results in lateral locking of the trial insert and trialcup such that the trial insert and trial cup cannot be uncoupled byoffsetting the longitudinal axis of the centering member of the trialcup and central axis of the trial insert. Further still, rotating thetrial insert another 90° in either a first or second radial directionabout the central axis thereof results in lateral unlocking of the trialinsert and trial cup such that the trial insert and trial cup can beuncoupled by offsetting the longitudinal axis of the centering member ofthe trial cup and central axis of the trial insert.

In another embodiment of this second aspect, a size or height of thetrial assembly is measured by the axial distance between a proximal endsurface of the trial insert and the distal end surface of the trial cup.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the subject matter of the presentinvention and the various advantages thereof can be realized byreference to the following detailed description in which reference ismade to the accompanying drawings in which:

FIG. 1 is an exploded perspective view of one embodiment of a trialassembly of the present invention including a trial cup and a trialinsert.

FIG. 2 is an assembled perspective view of one embodiment of a trialassembly of the present invention including the trial cup and the trialinsert of FIG. 1.

FIG. 3 is a side view of the trial assembly shown in FIG. 2.

FIG. 4A is a perspective view of one embodiment of a trial cup of thepresent invention.

FIG. 4B is a side view of the trial cup shown in FIG. 4A.

FIG. 4C is a top view of the trial cup shown in FIG. 4A.

FIG. 4D is a bottom view of the trial cup shown in FIG. 4A.

FIG. 5A is a perspective view of one embodiment of a trial insert of thepresent invention.

FIG. 5B is a side view of the trial insert shown in FIG. 5A.

FIG. 5C is a top view of the trial insert shown in FIG. 5A.

FIG. 5D is a bottom view of the trial insert shown in FIG. 5A.

FIG. 6A is an exploded view of an implant cup and trial insert.

FIG. 6B is an assembled view of the implant cup and trial insert shownin FIG. 6A.

FIG. 7A is an exploded view of a broach, trial cup and trial insert.

FIG. 7B is an assembled view of the broach, cup and trial insert shownin FIG. 7A.

FIG. 8A is an exploded view of an implant stem, implant cup and trialinsert.

FIG. 8B is an assembled view of the implant stem, implant cup and trialinsert shown in FIG. 8A.

FIG. 9A is an exploded view of an implant stem, trial cup and trialinsert.

FIG. 9B is an assembled view of the implant stem, trial cup and trialinsert shown in FIG. 9A.

DETAILED DESCRIPTION

Referring to FIGS. 1-3, there is shown an embodiment of a trial assemblyof the present invention designated generally by reference numeral 100.As shown in those figures, trial assembly 100 includes a trial cup 120and a trial insert 160.

FIGS. 4A-D show an embodiment of trial cup 120. As shown in thesefigures, trial cup 120 includes a distal end surface 122 and a proximalend surface 124. Proximal end surface 124 includes first and secondflanges 126, 128 and a centering member 130 protruding outwardlytherefrom. Proximal end surface 124 preferably includes a marker 144thereon as shown in FIG. 4D.

First and second flanges 126, 128 preferably extend outwardly from atleast a portion of an outer circumference 136 of proximal end surface124 of trial cup 120. First and second flanges 126, 128 include anengagement member 132, 134 respectively. Engagement members 132, 134preferably extend outwardly from inner surfaces of first and secondflanges 126, 128. Engagement members 132, 134 preferably include a topsurface 133, 135, respectively. As seen in FIGS. 4A and 4B, axis A1 is acentral longitudinal axis through centering member 130 and is also is acentral longitudinal axis for trial cup 120.

Protruding outwardly from distal end surface 122 of trial cup arepreferably first and second coupling members 140, 142. Coupling members140, 142 are configured to engage first and second recesses in a stem orelongate shaft (not shown) in order to couple the stem and trial cup120.

FIGS. 5A-D show an embodiment of trial insert 160. As shown in thesefigures, trial insert 160 includes a proximal end portion 162 and ashaft portion 164 having a distal end 166. Shaft portion 164 has agroove 168 around an outer circumference 170 thereof and a recess 172 inthe distal end 166 thereof. Recess 172 of trial insert 160 preferablybegins at outer circumference 170 of shaft portion 164 and preferablyterminates adjacent a central axis A2 of the trial insert 160.

As shown in FIG. 5C, proximal end portion 162 of trial insert 160 has aconcave recess 180 therein. Concave recess 180 is adapted to contact andhouse a portion of a glenosphere (not shown). Proximal end portion 162of trial insert 160 includes an outer face 182 preferably having aplurality of attachment locations 184 and calibration marks 186 arrangedthereon. The attachment locations 184 are preferably located at 30°increments about outer face 182, but may be located from one another atincrements greater or less than 30°. The calibration marks 186 arepreferably located at 90° increments about outer face 182, but may belocated from one another at increments greater or less than 90°.Attachment locations 184 are adapted to be engaged by an adjustment tool(not shown) for rotating the trial insert 160 about central axis A2thereof.

A reverse shoulder implant typically consists of five components: ahumeral stem, a humeral cup, a humeral insert, a glenosphere baseplate,and a glenosphere. The embodiment of trial assembly 100 shown in FIGS.1-3 includes two distinct components, namely trial cup 120 and trialinsert 160, which are designed to allow a surgeon to determine whichsize humeral cup and humeral insert are needed to provide a shoulderjoint with optimal deltoid tension in a RSA procedure. Both trial cup120 and trial insert 160 are designed to work with other components orparts of a reverse shoulder implant and instrumentation thereof as partof a complete system in order to give a surgeon intraoperativeflexibility and to accommodate surgeon preference. In addition, thedesign of trial cup 120 and trial insert 160 allows trial insert 160 toslide into trial cup 120 from a direction substantially transverse tothe direction of trial cup axis A1, which minimizes soft tissuestretching when reducing or dislocating a reverse shoulder during atrialing process, and gives a surgeon the ability to perform a trialingprocedure using instruments only or some combination of instruments andimplants.

The design of trial assembly 100 overcomes the challenge of soft tissuestretching when reducing or dislocating a joint by allowing the trialhumeral insert to slide into the trial humeral cup at an anglesubstantially transverse to the axis of the cup. Since the trial insert160 can enter the trial cup 120 at a transverse angle to trial cup axisA1, reduction or dislocation of the joint can be achieved without theneed to pull the glenosphere over the rim of trial insert 160. Softtissue stretching is therefore minimized.

In one method of the present invention, trial insert 160 is operativelycoupled to trial cup 120 when centering member 130 of trial cup 120 isreceived in recess 172 of trial insert 160 and an engagement member 132,134 on each of first and second flanges 126, 128 of trial cup 120 isreceived within groove 168 of trial insert 160. When centering member130 is located within recess 172 of trial insert 160 and longitudinalaxis A1 of centering member 130 is collinear with central axis A2 oftrial insert 160, trial insert 160 may be rotated in a radial directionabout central axis A2 thereof. The trial insert 160 can be reversiblylocked into the trial cup 120 simply by turning the trial insert 160approximately 15 degrees to approximately 165 degrees after initiallyengaging the trial insert 160 and trial cup 120. For example, after axesA1, A2 become collinearly oriented, rotating the trial insert 160approximately 90° in either a first or second radial direction aboutcentral axis A2 thereof results in lateral locking of trial insert 160and trial cup 120 such that trial insert 160 and trial cup 120 cannot beuncoupled by offsetting longitudinal axis A1 of the centering member 130of trial cup 120 and central axis A2 of trial insert 160. Rotating trialinsert 160 approximately another 90° in either a first or second radialdirection about central axis A2 thereof results in lateral unlocking oftrial insert 160 and trial cup 120 such that trial insert 160 and trialcup 120 can be uncoupled by offsetting longitudinal axis A1 of centeringmember 130 of trial cup 120 and central axis A2 of trial insert 160.

When operatively coupled, trial insert 160 can be rotated with respectto trial cup 120 by using an attachment tool having an end that can bereceived in attachment locations 184. A surgeon can estimate the amountof degrees that trial insert 160 has been rotated with respect to trialcup 120 by visualizing the movement of calibration marks 186 located onouter face 182 or by visualizing the movement of calibration marks 186with respect to marker 144 located on proximal end surface 124 of trialcup 120.

As shown in FIGS. 3 and 5B, a first height H1 is defined by the planardistance between a proximal end surface 161 and distal surface 163 ofproximal end portion 162 of trial insert 160. As shown in FIGS. 3 and4B, a second height H2 is defined by the planar distance between a topsurface 133, 135 of engagement members 132, 134 and distal end surface122 of trial cup 120. A size or height H of trial assembly 100 ismeasured by the axial or planar distance between proximal surface 161 oftrial insert 160 and distal end surface 122 of trial cup 120 as shown inFIG. 3.

During the trial process, a surgeon may use one or more of a pluralityof different sized trial cups and inserts. Each insert 160 preferablyhas a first height H1 between 4 mm and 12 mm in increments of 2 mm asshown in the chart below. A surgeon may then use one or more of aplurality of different sized trial cups 120. Each cup 120 preferably hasa second height H2 that is either 4 mm or 10 mm as shown in the chartbelow. The following chart is a non-limiting example of the differentsized trial inserts 160, trial cups 120 and the resultant total height H(8 mm, 10 mm, 12 mm, 14 mm, 16 mm, 18 mm, 20 mm and 22 mm) that can beachieved when trial inserts 160 and trial cups 120 are assembled andused during the trialing process:

4 mm 6 mm 8 mm 10 mm 12 mm Insert Insert Insert Insert Insert  4 mm Cup8 10 12 14 16 10 mm Cup 14 16 18 20 22

The design of trial assembly 100 overcomes the challenge of having onesystem allowing multiple intraoperative options with regard to trialingby allowing the trial cup 120 to be connected to either a broach 200 asshown in FIGS. 7A-B or humeral stem implant 220 as shown in FIGS. 9A-B,and also by allowing the trial insert 160 to be able to be connected toeither trial cup 120 or implant cup 190 as shown in FIGS. 6A-6B and8A-8B.

Surgeon preferences result in implants and instruments being used indifferent combinations. For example, some surgeons prefer to perform thetrialing procedure off of a broach including cutting portions 210 suchas teeth, for example, as shown in FIGS. 7A-7B used to create a cavityinto which a humeral stem implant will eventually be placed. Somesurgeons instead prefer to trial off of the humeral stem itself as shownin FIGS. 8A-8B and 9A-9B. As a result, it is advantageous for any trialhumeral cup to be able to be connected to both the broach and humeralstem implant. Likewise, some surgeons prefer to perform the trialingprocedure off of a trial humeral cup and some surgeons prefer to trialoff of the humeral cup implant. Therefore it is advantageous for thehumeral insert trial to be able to be connected to both the trialhumeral cup and the humeral cup implant.

The same trial insert 160 that can be slid into engagement with trialcup 120 at an angle transverse to trial cup axis A1 can also be droppedinto a humeral cup implant along an axis coincident with both thehumeral cup implant and trial insert 160. The attachment mechanisms thatpermit a connection between an implant component and a trial do notcompromise the integrity of the attachment mechanisms used to connecttwo implant components. Such a design allows a surgeon to trial off ofan implant with confidence that the trialing procedure is not damagingthe implant attachment mechanisms which could possibly compromise theperformance of the implant after final assembly.

In other embodiments, trial insert 160 may be able to engage trial cup120 by sliding in a lateral direction into engagement with the trial cup120, with trialing occurring as the trial insert 160 expands away fromand collapses toward trial cup 120. For example, groove 168 of trialinsert 160 may be in the form of a helical groove about shaft portion164. The motion of trial insert along axis A1 of trial cup 120 may beguided by the interaction between the helical groove and an engagementmember 133 or 125, for example. In such an embodiment, centering member130 of trial cup 120 will have a larger height and recess 172 of trialinsert 160 will have a greater depth such that the centering member 130will remain at least partially within recess 172 as trial insert 160expands and collapses with respect to trial cup 120.

The interaction of the helical groove and engagement member occurs muchlike that shown in U.S. Pat. Pub. No. 2009/0099662 titled “ExpandableReverse Shoulder Trial,” the disclosure of which is hereby incorporatedby reference in its entirety. When trial insert 160 first becomesoperatively engaged to trial cup 120, trial insert 160 may then berotated into a fully collapsed or neutral position. Such a device mayallow a surgeon to easily reduce the shoulder joint.

Preferably, trial insert 160 may then be advanced to a position whereoptimal deltoid tension is achieved. At this position, the trial insert160 and trial cup 120 are preferably calibrated such that the surgeonmay determine a liner thickness corresponding to a dialed position ofthe insert with respect to the cup.

Preferably, the surgeon may then easily collapse the trial back to theneutral position and simply dislocate the joint. Further, the trial mayalso be preferably expanded prior to joint reduction and collapsed priorto joint dislocation repeatedly, depending on surgeon preference. Oncethe trial has been optimized, a surgeon preferably records the dialedposition of the expanded trial. This measurement should preferably bethe liner thickness. If this measurement does not correspond to the sizeof a particular liner in the system, the surgeon may select a nextlarger sized liner. At this time, the surgeon may remove the trial andthen implant a prosthesis including a humeral cup and the selectedliner.

The embodiments described herein have applications in RSA as well as anyother ball and socket joints that require dislocation and reduction,such as hip joints for example.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

1. A reverse shoulder system comprising: at least one stem member havinga shaft portion adapted to be received in a canal of a humeral bone of apatient; a trial cup and a prosthesis cup each adapted to be coupled ata distal end thereof to the at least one stem member, the trial cup andprosthesis cup each having a distal end surface, a base surface and aproximal end surface; a trial insert and a prosthesis insert eachincluding a proximal end portion having a proximal end surface and ashaft portion having a distal end surface, wherein a linear trialdistance is measured between the distal end surface of the trial cup andthe proximal end surface of the trial insert when the trial insert isoperatively coupled to the trial cup such that the distal end surface ofthe shaft portion of the trial insert lies adjacent to the base surfaceof the trial cup, and wherein a linear prosthesis distance is measuredbetween the distal end surface of the prosthesis cup and the proximalend surface of the prosthesis insert when the prosthesis insert isoperatively coupled to the prosthesis cup such that the distal endsurface of the shaft portion of the prosthesis insert lies adjacent tothe base surface of the prosthesis cup, and wherein the linear trialdistance is substantially the same as the linear prosthesis distance. 2.The reverse shoulder system of claim 1, wherein the at least one stemmember is a broach.
 3. The reverse shoulder system of claim 1, whereinthe at least one stem member is a humeral implant.
 4. The reverseshoulder system of claim 1, wherein the at least one stem member is abroach and a humeral implant.
 5. The reverse shoulder system of claim 1,wherein the at least one stem member has a proximal end including anengagement member and the distal end portion of both the trial cup andprosthesis cup include an engagement member configured to engage to theengagement member of the at least one stem member in order to coupleeither the at least one stem member and trial cup or at least one stemmember and prosthesis cup.
 6. The reverse shoulder system of claim 1,wherein the trial cup includes first and second flanges and a centeringmember protruding outwardly from the base surface, the shaft portion ofthe trial insert includes a groove around an outer circumference thereofand a recess in the distal end thereof, and wherein the trial insert isoperatively coupled to the trial cup when the centering member isreceived in the recess of the trial insert and an engagement member oneach of the first and second flanges is received within the groove ofthe trial insert.
 7. The reverse shoulder system of claim 6, wherein thefirst and second flanges of the trial cup extend outwardly from at leasta portion of an outer circumference of the base surface of the trialcup.
 8. The reverse shoulder system of claim 6, wherein the recess ofthe trial insert begins at the outer circumference of the shaft portionand terminates adjacent a central axis of the trial insert.
 9. Thereverse shoulder system of claim 8, wherein when a longitudinal axis ofthe centering member is collinear with the central axis of the trialinsert, the trial insert may be rotated in a radial direction about thecentral axis thereof.
 10. The reverse shoulder system of 9, whereinrotating the trial insert 90° in either a first or second radialdirection about a central axis thereof results in lateral locking of thetrial insert and trial cup such that the trial insert and trial cupcannot be uncoupled by offsetting the longitudinal axis of the centeringmember of the trial cup and central axis of the trial insert.
 11. Thereverse shoulder system of 10, wherein rotating the trial insert another90° in either a first or second radial direction about the central axisthereof results in lateral unlocking of the trial insert and trial cupsuch that the trial insert and trial cup can be uncoupled by offsettingthe longitudinal axis of the centering member of the trial cup andcentral axis of the trial insert.
 12. The reverse shoulder system ofclaim 1, wherein the proximal end surface of both the trial insert andprosthesis insert have a concave recess portion.
 13. The reverseshoulder system of claim 1, wherein an outer face of the trial insertadjacent the proximal end surface thereof includes a plurality ofattachment locations adapted to be engaged by an adjustment tool. 14.The reverse shoulder system of claim 1, wherein an outer face of theproximal end portion of the trial insert has a plurality of calibrationmarks arranged thereon.
 15. The reverse shoulder system of claim 14,wherein the calibration marks are located at 90° increments.
 16. Thereverse shoulder system of claim 1, wherein an outer face of theproximal end portion of the trial insert includes a plurality ofattachment locations adapted to be engaged by an adjustment tool forrotating the trial insert about the central axis thereof.
 17. Thereverse shoulder system of claim 1, wherein the proximal end surface ofthe cup has at least one marker thereon.
 18. A reverse shoulder systemcomprising: at least one stem member having a shaft portion adapted tobe received in a canal of a humeral bone of a patient; a trial cup and aprosthesis cup each adapted to be coupled at a distal end thereof to theat least one stem member, the trial cup and prosthesis cup each having adistal end surface, a base surface and a proximal end surface; a trialinsert and a prosthesis insert each including a proximal end portionhaving distal and proximal end surfaces and a shaft portion having adistal end surface, wherein a linear trial distance is measured betweenthe proximal end surface of the trial cup and the proximal end surfaceof the trial insert when the trial insert is operatively coupled to thetrial cup such that the distal end surface of the proximal end portionof the trial insert lies adjacent to the proximal end surface of thetrial cup, wherein a linear prosthesis distance is measured between theproximal end surface of the prosthesis cup and the proximal end surfaceof the prosthesis insert when the prosthesis insert is operativelycoupled to the prosthesis cup such that the distal end surface of theproximal end portion of the prosthesis insert lies adjacent to theproximal end surface of the prosthesis cup, and wherein the linear trialdistance is substantially the same as the linear prosthesis distance.19. A method of using trial inserts of a reverse shoulder system todetermine a height of a prosthesis cup to achieve proper deltoid tensioncomprising: inserting a shaft portion of a stem member in a canal of ahumeral bone of a patient; coupling a cup member at a distal end thereofto the stem member, the cup member having a base surface and a proximalend surface; selecting trial inserts having a proximal end portionincluding proximal and distal end surfaces and a shaft portion having adistal end surface, a height of each of the trial insert defined by theplanar distance between the proximal and distal end surfaces of theproximal end portion of the trial insert; coupling the trial inserts oneat a time to the cup member, each of the trial inserts being operativelycoupled to the cup member when the distal end surface of the shaftportion of each of the trial inserts lies adjacent to the base surfaceof the cup member; determining which of the trial inserts whenoperatively coupled to the cup member achieves proper deltoid tensionand noting the height thereof; uncoupling the trial insert and cupmember; and coupling a prosthesis insert to the cup member such that adistal end surface of a shaft portion of the prosthesis insert liesadjacent to the base surface of the cup member, the height of theprosthesis insert defined by the planar distance between proximal anddistal end surfaces of a proximal end portion of the prosthesis insert,wherein the height of the prosthesis insert is substantially the same asthe height of the trial insert.